JP2019167051A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire in which generation of pattern noise is suppressed and of which snow performance can be improved while suppressing decrease in a block rigidity.SOLUTION: Plural sipes 11A, 11C, which are inclined with respect to a tire width direction, are provided on a center land part 10A and a shoulder land part 10C respectively, and plural lug grooves 21 having a sharp bent part 22 and plural sipes 11B, which extend in a direction intersecting these lug grooves 21, are provided on an intermediate land part 10B. Respective lug grooves 21 are so located as to be not overlapped on one another in a tire circumferential direction in such a manner that one end 21a of each lug groove is opened to an outer side main groove 9B, and on the other hand, the other end 21b thereof is terminated in the intermediate land part 10B. A groove width t2 of the sipe 11C of the intermediate land part 11B is narrower than a groove width t1, t3 of each sipe 11A, 11C of the center land part 10A and the shoulder land part 10C.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire suitable as an all-season tire. More specifically, the present invention relates to a pneumatic tire that can suppress the occurrence of pattern noise and improve snow performance while suppressing a decrease in block rigidity. .

  All-season tires are required to exhibit excellent snow performance during snowfall. In contrast, in the conventional all-season tire, by providing a plurality of lug grooves having a bent shape in the land portion of the tread portion, the edge component due to the groove acts in all directions, and the land portion of the tread portion. A snow performance is improved by providing a plurality of sipes on the surface (for example, see Patent Document 1).

  However, when a plurality of lug grooves having a bent shape are provided in the tread portion, there is a problem that the block rigidity is lowered. Further, depending on the arrangement of the sipe provided in the tread portion, a decrease in block rigidity may be promoted. And there exists a problem that it becomes easy to generate | occur | produce pattern noise resulting from the fall of block rigidity. Further, when the block rigidity is lowered, the wear resistance is deteriorated and the steering stability performance on the dry road surface tends to be deteriorated.

JP 2014-205410 A

  An object of the present invention is to provide a pneumatic tire that can suppress the occurrence of pattern noise and improve snow performance while suppressing a decrease in block rigidity.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. And four main grooves including a pair of inner main grooves and a pair of outer main grooves extending in the tire circumferential direction are provided in the tread portion. In the pneumatic tire in which a center land portion, a pair of intermediate land portions positioned outside the center land portion, and a pair of shoulder land portions positioned outside the intermediate land portion are partitioned by a groove, the center land portion and A plurality of sipes are provided in each of the shoulder land portions at intervals in the tire circumferential direction, and a plurality of lug grooves having acute bent portions are intersected with the lug grooves in the intermediate land portion. Direction A plurality of sipes extending to each of the lugs, each lug groove having one end opened to the outer main groove and the other end terminating in the intermediate land portion, and in the tire circumferential direction. They are arranged without overlapping each other, and the groove width of the sipe in the intermediate land portion is narrower than the groove width of each sipe in the center land portion and the shoulder land portion.

  In the present invention, a plurality of sipes are provided in each of the center land portion and the shoulder land portion at intervals in the tire circumferential direction, and a plurality of lug grooves having acute bent portions in the intermediate land portion, and these lugs A plurality of sipes extending in a direction crossing the groove, and each lug groove has one end opened to the outer main groove while the other end terminates in the intermediate land portion. Since the tires are arranged in the tire circumferential direction without overlapping each other, it is possible to improve snow performance (particularly, steering stability performance on a road surface on snow) while suppressing a decrease in block rigidity. In addition, the block rigidity is locally reduced by the sipe intersecting the lug groove in the middle land portion, but the groove width of the sipe in the middle land portion is larger than the groove width of each sipe in the center land portion and the shoulder land portion. Since it is set narrowly, the fall of the block rigidity in an intermediate land part can be suppressed, and generation | occurrence | production of pattern noise can be suppressed. Further, since the decrease in block rigidity can be suppressed, the wear resistance can be improved and the steering stability performance on the dry road surface can be improved.

  In the present invention, the direction of the sipe of the center land portion and the shoulder land portion with respect to the tire width direction is preferably opposite to the sipe of the intermediate land portion. Thereby, generation | occurrence | production of pattern noise can be suppressed effectively.

  In the present invention, it is preferable that the width W1 of the center land portion, the width W2 of the intermediate land portion, and the width W3 in the ground contact region of the shoulder land portion satisfy a relationship of W1 <W2 <W3. Thereby, the width | variety of a middle land part can be ensured comparatively widely, and the steering stability performance on a dry road surface can be improved effectively.

  In the present invention, the shoulder land portion is provided with a plurality of lug grooves at intervals in the tire circumferential direction, and the total number of lug grooves and sipes in the shoulder land portion is preferably larger than the number of sipes in the intermediate land portion. . Thereby, generation | occurrence | production of pattern noise can be suppressed effectively, increasing the groove number in a shoulder land part relatively, and suppressing the fall of the block rigidity in an intermediate land part.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is a top view which shows an example of the tread part of the pneumatic tire which consists of embodiment of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a pneumatic tire according to an embodiment of the present invention. In FIG. 2, Tc indicates the tire circumferential direction, and Tw indicates the tire width direction.

  As shown in FIG. 1, a pneumatic tire according to an embodiment of the present invention includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions that are disposed on both sides of the tread portion 1. 2 and 2 and a pair of bead portions 3 and 3 disposed on the inner side in the tire radial direction of the sidewall portions 2.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIG. 2, four main grooves 9 extending in the tire circumferential direction are formed in the tread portion 1. The main groove 9 includes a pair of inner main grooves 9A and 9A located on both sides of the tire center line CL, and a pair of outer main grooves 9B and 9B located on the outermost side in the tire width direction. These four main grooves 9 define a land portion 10 in the tread portion 1. The land portion 10 includes a center land portion 10A located on the tire center line CL, a pair of intermediate land portions 10B and 10B located on the outer side in the tire width direction of the center land portion 10A, and a tire width direction of each intermediate land portion 10B. It includes a pair of shoulder land portions 10C, 10C located outside.

  In the center land portion 10A, a plurality of sipes 11A and a plurality of narrow grooves 31 that are inclined in the same direction with respect to the tire width direction are formed at intervals in the tire circumferential direction. One end of the sipe 11A communicates with the inner main groove 9A, and the other end communicates with the narrow groove 31. That is, the sipe 11A is an open sipe. On the other hand, the narrow groove 31 is a groove having a groove width wider than that of the sipe 11A. The narrow groove 31 has one end communicating with the inner main groove 9A and the other end communicating with the sipe 11A. Such sipes 11A and narrow grooves 31 are alternately arranged in the tire circumferential direction, and the narrow grooves 31 as a whole in the center land portion 10A are arranged in a staggered manner in the tire circumferential direction.

  In the intermediate land portion 10B, a plurality of lug grooves 21 inclined in the same direction with respect to the tire width direction are formed at intervals in the tire circumferential direction. These lug grooves 21 have one end 21a that opens to the outer main groove 9B, while the other end 21b terminates in the intermediate land portion 10B. Each of the lug grooves 21 is disposed without overlapping each other in the tire circumferential direction. Moreover, the lug groove 21 has the bending part 22 formed in acute angle shape in the middle position of one edge part 21a and the other edge part 21b.

  In the intermediate land portion 10B, a plurality of sipes 11B extending in a direction intersecting the lug grooves 21 are formed at intervals in the tire circumferential direction. The sipe 11B has a structure that is divided into a plurality of parts by penetrating the lug grooves 21, and the divided parts in the same sipe 11B are arranged on the same straight line. As for the sipe 11B as a whole, one end portion communicates with the inner main groove 9A, and the other end portion communicates with the outer main groove 9B. That is, the sipe 11B is an open sipe.

  A plurality of lug grooves 24 that are inclined in the same direction with respect to the tire width direction are formed in the shoulder land portion 10C at intervals in the tire circumferential direction. These lug grooves 24 are not in communication with the outer main groove 9B. Further, a plurality of sipes 11C that are inclined in the same direction with respect to the tire width direction are formed in the shoulder land portion 10C at intervals in the tire circumferential direction. Both ends of these sipes 11C terminate in the shoulder land portion 10C. That is, the sipe 11C is a closed sipe.

  In the pneumatic tire, the groove width of the sipe 11A of the center land portion 10A is t1, the groove width of the sipe 11B of the intermediate land portion 10B is t2, and the groove width of the sipe 11C of the shoulder land portion 10C is t3. At this time, the groove width t2 of the sipe 11B of the intermediate land portion 10B is configured to be narrower than the groove width t1 of the sipe 11A of the center land portion 10A and the groove width t3 of the sipe 11C of the shoulder land portion 10C. At that time, the groove width t1 of the sipe 11A of the center land portion 10A and the groove width t3 of the sipe 11C of the shoulder land portion 10C may be set to the same groove width or different groove widths. Also good. In particular, the groove width t2 of the sipe 11B of the intermediate land portion 10B is set to 0.5 to 0.8 times the groove width t1 of the sipe 11A of the center land portion 10A and the groove width t3 of the sipe 11C of the shoulder land portion 10C. It is preferable. The sipe 11 is a groove having a groove width of 1.5 mm or less.

  In the pneumatic tire described above, a plurality of sipes 11A and 11C are provided in the center land portion 10A and the shoulder land portion 10C at intervals in the tire circumferential direction, and an acute bent portion 22 is provided in the intermediate land portion 10B. A plurality of lug grooves 21 and a plurality of sipes 11B extending in a direction intersecting with the lug grooves 21 are provided, and each lug groove 21 has one end 21a in the outer main groove 9B. While opening, the other end portion 21b terminates in the intermediate land portion 10B and is disposed so as not to overlap each other in the tire circumferential direction. It is possible to improve the steering stability performance on the road surface. In addition, the block rigidity is locally reduced by passing the sipe 11B through the lug groove 21 in the intermediate land portion 10B, but the groove width t2 of the sipe 11B of the intermediate land portion 10B is the groove width of the sipe 11A of the center land portion 10A. Since it is set narrower than t1 and the groove width t3 of the sipe 11C of the shoulder land portion 10C, a decrease in block rigidity in the intermediate land portion 10B can be suppressed, and generation of pattern noise can be suppressed. Further, since the decrease in block rigidity can be suppressed, the wear resistance can be improved and the steering stability performance on the dry road surface can be improved.

  In the pneumatic tire, as shown in FIG. 2, the sipe 11A of the center land portion 10A and the sipe 11C of the shoulder land portion 10C with respect to the tire width direction are opposite to the sipe 11B of the intermediate land portion 10B. By configuring the sipes 11A to 11C of the land portions 10A to 10C in this way, generation of pattern noise can be effectively suppressed. Here, if the directions of the sipe 11A to 11C of the land portions 10A to 10C with respect to the tire width direction are all the same, it tends to overlap with the ground contact front line, and the pattern noise tends to deteriorate.

  Further, the width W1 of the center land portion 10A, the width W2 of the intermediate land portion 10B, and the width W3 in the ground contact region of the shoulder land portion 10C are configured to satisfy the relationship of W1 <W2 <W3. By setting the widths W1 to W3 of the land portions 10A to 10C so as to satisfy such a relationship, the width W2 of the intermediate land portion 10B can be secured relatively wide, and the steering stability performance on the dry road surface can be ensured. It can be effectively improved. Here, if the width W3 of the shoulder land portion 10C is too narrow, the steering stability performance and the braking performance on the dry road surface tend to be lowered.

  The width W3 in the ground contact area of the shoulder land portion 10C is specifically the width from the end on the outer main groove 9B side of the shoulder land portion 10C to the ground end E. The ground contact edge E is the outermost position in the tire width direction of the ground contact region. The ground contact area is defined as the maximum load capacity stipulated for each tire according to the standard on which the tire is based (JATMA, TRA, ETRTO, etc.). This is a region in the tire width direction corresponding to the maximum linear distance in the tire width direction on the contact surface formed on the flat plate when a load corresponding to 80% of the load capacity is applied.

  Further, the total number N2 of lug grooves 24 and sipes 11C in the shoulder land portion 10C is formed larger than the number N1 of sipes 11B in the intermediate land portion 10B. In particular, the total number N2 of lug grooves 24 and sipes 11C in the shoulder land portion 10C is preferably set to 1.1 to 1.3 times the number N1 of sipes 11B in the intermediate land portion 10B. By comprising in this way, generation | occurrence | production of pattern noise can be suppressed effectively, increasing the groove number in 10 C of shoulder land parts relatively, and suppressing the fall of the block rigidity in the intermediate land part 10B. Here, when the total number N2 of lug grooves 24 and sipes 11C in the shoulder land portion 10C and the number N1 of sipes 11B in the intermediate land portion 10B are set to the same number, there is a tendency that pattern noise is remarkably generated. On the other hand, if the number N1 of the sipes 11B in the intermediate land portion 10B is larger than the total number N2 of the lug grooves 24 and the sipes 11C in the shoulder land portion 10C, the block rigidity is lowered, which is not preferable. The number N1 of sipes 11B in the intermediate land portion 10B and the total number N2 of lug grooves 24 and sipes 11C in the shoulder land portion 10C are the number of target grooves included in the entire tire circumference of each land portion.

  Tire size 225 / 50R18, an annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and disposed in the tire radial direction inside these sidewall portions. And four main grooves including a pair of inner main grooves and a pair of outer main grooves extending in the tire circumferential direction are provided in the tread portion. In a pneumatic tire in which a pair of intermediate land portions located outside the portion and a pair of shoulder land portions located outside the intermediate land portion are partitioned, each of the center land portion and the shoulder land portion is arranged in the tire width direction. A plurality of sipes that are inclined with respect to each other are provided, and a plurality of lug grooves having acute bent portions in the intermediate land portion, and a plurality of sipes extending in a direction intersecting the lug grooves. The lug grooves are arranged such that one end portion opens into the outer main groove while the other end ends in the intermediate land portion and does not overlap each other in the tire circumferential direction. The groove width of the sipe at the center is narrower than the groove width of the sipe at each of the center land portion and the shoulder land portion, the groove width t2 of the sipe at the intermediate land portion, the groove width t1 of the sipe at the center land portion, Groove width t3, the inclination direction of each sipe with respect to the tire width direction, the size relationship between the widths W1, W2, and W3 of each land part, the lug groove of the shoulder land part and the sipe of the sipe of the intermediate land part N1 Conventional tires and tires of Examples 1 to 4 in which the ratio (N2 / N1) of the total number N2 was set as shown in Table 1 were manufactured.

  These test tires were subjected to sensory evaluation on the driving stability performance on snowy road surfaces, pattern noise and driving stability performance on dry road surfaces by test drivers, and the results are also shown in Table 1.

  The sensory evaluation regarding the steering stability performance on the road surface on snow was performed by assembling each test tire on a rim size 18 × 7J wheel and mounting it on a front-wheel drive vehicle. The evaluation results are shown as 10-level evaluation values. The larger this evaluation value, the better the steering stability performance on the road surface on snow.

  Sensory evaluation regarding pattern noise was performed by assembling each test tire on a rim size 18 × 7J wheel and mounting it on a front-wheel drive vehicle. The evaluation results are shown as 10-level evaluation values. The larger the evaluation value, the better the suppression effect on the occurrence of pattern noise.

  Sensory evaluation regarding the driving stability performance on a dry road surface was performed by assembling each test tire on a rim size 18 × 7J wheel and mounting it on a front-wheel drive vehicle. The evaluation results are shown as 10-level evaluation values. The larger this evaluation value, the better the steering stability performance on the dry road surface.

  As can be seen from Table 1, in the tires of Examples 1 to 4, the steering stability performance on the road surface on the snow, the pattern noise, and the steering stability performance on the dry road surface were improved in a well-balanced manner as compared with the conventional tires.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 9 Main groove 9A Inner main groove 9B Outer main groove 10 Land part 10A Center land part 10B Middle land part 10C Shoulder land part 11A, 11B, 11C Sipe 21 Lug groove 22 Bending part t1, t2, t3 Groove width CL Tire center line E Grounding end

Claims (4)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. And four main grooves including a pair of inner main grooves and a pair of outer main grooves extending in the tire circumferential direction are provided in the tread portion, and are located outside the center land portion and the center land portion by these main grooves. In a pneumatic tire in which a pair of intermediate land portions and a pair of shoulder land portions located outside the intermediate land portions are partitioned,
Each of the center land portion and the shoulder land portion is provided with a plurality of sipes at intervals in the tire circumferential direction, the intermediate land portion having a plurality of lug grooves having sharp bent portions, and these lug grooves A plurality of sipes extending in a direction intersecting with each other, and each lug groove has one end opened to the outer main groove while the other end terminates in the intermediate land portion. And the sipe groove width of the middle land portion is narrower than the sipe groove width of each of the center land portion and the shoulder land portion. tire.   2. The pneumatic tire according to claim 1, wherein the sipe of the center land portion and the shoulder land portion with respect to the tire width direction is opposite to the sipe of the intermediate land portion.   The width W1 of the center land portion, the width W2 of the intermediate land portion, and the width W3 of the shoulder land portion in the ground contact region satisfy a relationship of W1 <W2 <W3. The described pneumatic tire.   The shoulder land portion is provided with a plurality of lug grooves at intervals in the tire circumferential direction, and the total number of lug grooves and sipes in the shoulder land portion is larger than the number of sipes in the intermediate land portion. The pneumatic tire according to any one of claims 1 to 3.

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